1. Field of the Invention
Embodiments of the invention relate to a flat panel display device and a method of fabricating the same, and particularly, to a flat panel display device capable of reducing damage that may be done to a wiring region in which link lines are formed in cutting an upper film in order to open a pad part, and a method of fabricating the same.
2. Description of the Related Art
Recently, flexible displays fabricated to be bent, curved, warped, or the like, by using a substrate made of a flexible material such as plastic, or the like, have emerged as next-generation display devices to meet the demand for being employed in portable products such as electronic sheets, arm bands, wallets, notebook computers, and the like.
A flexible display is one of next-generation displays implemented on a thin substrate such as a plastic substrate so as to be folded or rolled like paper without being damaged, and currently, an organic light emitting diode (OLED) display that can be fabricated to have a thickness equal to or less than 1 mm looks promising.
An OLED display, being a self-luminous device, has good visibility in a dark area or even in the presence of ambient light. A response speed is an important barometer for determining performance of a mobile display, and since an OLED display has the fastest response speed, among available displays, the OLED display can display high quality video. Also, an OLED display is available in an ultra-thin design, making various mobile devices employing such an OLED display thinner. Hereinafter, a schematic structure of an OLED display will be described with reference to the accompanying drawings.
FIGS. 1A and 1B are schematic cross-sectional views according to a related art OLED display. First, referring to FIG. 1A, an OLED display includes a first substrate 10 in which a thin film transistor (TFT) and an OLED are formed and a second substrate 20 encapsulating a region in which the TFT and the OLED are formed. In this instance, in order to encapsulate the TFT and the OLED, an adhesive, or the like, may also be used instead of the second substrate 20.
When the OLED display is used as a flexible device, the first substrate 10 may be made of a plastic material. The first substrate 10 may be defined by a display region and a non-display region. A plurality of pixels including TFTs are formed in the display region and a driving circuit unit 10p for driving the plurality of pixels through the TFTs of the display region is formed in the non-display region. Thereafter, an OLED layer is formed in the display region. The OLED layer emits light of various colors under the control of the driving circuit unit 10p and the TFTs.
The second substrate 20 is formed to have a size corresponding to the display region, and this is to expose a space in which the driving circuit unit 10p is connected to a printed circuit board (PCB). The driving circuit unit 10p includes a plurality of pads formed to be connected to wirings of the display region, and the driving circuit unit 10p is connected to the PCB through the pads.
Thus, among an upper film 51 and a lower film 52 attached after the first substrate 10 and the second substrate 20 are attached, a region of the upper film 51 corresponding to the driving circuit unit 10p is required to be open. The upper film 51 and the lower film 52 may be protective films or polarizer films (or polarizing films) and have an area corresponding to the entire surface of the OLED display. When first attached, the region of the upper film 51 covers the driving circuit unit 10p. Thus, in order to remove the region of the upper film 51 covering the driving circuit unit 10p, a cutting process is performed on the region of the upper film 51.
The cutting process includes a method of using wet etching and a method of using a laser.
The method of using wet etching has difficulty in cutting a film having a fine area, and has a problem in relation to cost of an etching solution and processing of used etching solution.
Thus, the method of using a laser is preferred to wet etching. However, the method of using a laser has a problem in that a laser unit is pricy and a region in which link lines are formed may be affected. This will be described with reference to FIG. 1B.
The reason for using a laser in cutting the upper film 51 is to perfectly cut-off the region of the upper film 51. Namely, in the instance of a glass substrate or an insulating substrate, marks may be formed due to hard material characteristics of the substrate and the substrate may be subsequently twisted so as to be cut along the marks. However, in the instance of a film, this method cannot be used due to the flexible characteristics of the film, so in order to perfectly cut the film, a laser is selectively used.
Here, a laser beam is shot from above the upper film 51 (or a laser beam is focused on the upper film 51). A region to which a laser beam is shot may be a region overlapped with a region ‘A’ in which link lines connecting pads of the driving circuit unit 10p and the wirings of the display region are formed.
However, the moment the upper film 51 is completely cut, the laser beam may be directly shot to the region ‘A’ in which the link lines of the first substrate 10 are formed. At this time, the laser beam shot to the region ‘A’ in which the link lines are formed may damage the link lines. Since the link lines are configured to transfer signals for driving the plurality of pixels, damage to the link lines may cause a defective image to be displayed on the OLED display.